jomance's Identifications

Dense patches of Yellow-flowering primrose plants growing at bottom of steep bank at Boy Scout Lake on Fort Ord Nat'l Monument.

Floating Primrose-Willow (Ludwigia peploides) a.k.a. Yellow Water-weed. INVASIVE.

Flora of Fort Ord: Monterey County, California, David Styer, 2019, p. 154.
(The subspecies is Ludwigia peploides ssp. peploides a.k.a. Yellow Water-weed)

Link to confirmed observation of Floating Primrose-Willow at Boy Scout Lake a few years ago: https://www.inaturalist.org/observations/56651910

Calflora (includes species distribution map in CA): https://www.calflora.org/app/taxon?crn=5084
Lists 2 subspecies.

Jepson eFlora https://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=51359
(only lists ssp. no species name)

Cal-IPC: Invasive Plants in CA: https://www.cal-ipc.org/plants/profile/ludwigia-peploides-profile/

Ludwigia peploides a.k.a. Yellow Water-weed, Marsh Purslane, Floating Water Primrose, California Waterprimrose, and Creeping Water Primrose. Synonyms: Jussiaea peploides. "It is a perennial aquatic plant (family Onagraceae) that forms very dense, virtually impenetrable mats which restrict fishing and boat access. It also out competes native aquatic plants. Ludwigia peploides can be found throughout California in rice fields, ditches, ponds, slow moving streams, and along edges of lakes and reservoirs. There is some confusion as to which non-native species occur in California and more than one, yet unknown, species may be invasive. Cal-IPC Rating: High"
Cal-IPC: Invasive Plants in CA: https://www.cal-ipc.org/plants/profile/ludwigia-peploides-profile/

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Calflora (includes species distribution maps in CA) https://www.calflora.org/search.html
Jepson eFlora (CA native and naturalized plants with botanical illustrations) https://ucjeps.berkeley.edu/eflora/
Plants of Monterey County: an Illustrated Field Key, 2nd edition, Matthews and Mitchell,2015 (2300+ species)
Monterey County Wildflowers (includes wildflowers, shrubs and trees) https://montereywildflowers.com/index/
Monterey County Wildflowers: a Field Guide, Yeager and Mitchell, 2016 (950+ species with photos)
Flora of Fort Ord: Monterey County, California, David Styer, 2019 (includes peak bloom times)
Jepson Manual: Vascular Plants of California, 2nd ed, 2012 (1568 pages, 6.4 lbs)
Flora of North America http://beta.floranorthamerica.org/Main_Page (search by scientific name)
Native American Ethnobotany: Traditional Native Plant Uses (medicines, foods, fibers, tools): http://naeb.brit.org/
Leaf Terminology: Diagrams/Definitions: https://upload.wikimedia.org/wikipedia/commons/e/e8/Leaf_morphology.svg
Plant Identification Terminology: An Illustrated Glossary, 2nd ed., by James Harris and M. Harris, 2022
Cal-IPC: Invasive Plants in CA (400+ species, Click on the scientific name/photo https://www.cal-ipc.org/plants/profiles/#